An innovative methodology for determining origin-based components of the water cycle: Application to the Zanjan alluvial aquifer, Iran
Year: 2025
Type: article
Abstract: • A novel methodology is presented to quantify water cycle components based on origin • It integrates a modified Thornthwaite-Mather approach and unsaturated zone modeling • It provides information to estimate four key coefficients for groundwater management • Precipitation-originated coefficients are precipitation percolation and effective precipitation • Irrigation-originated coefficients are irrigation return flow and application efficiency Distinguishing the origins of water balance components remains a key challenge in groundwater management, particularly in arid and semi-arid environments. This study introduces a novel methodological framework for separating precipitation and irrigation-originated components of actual evapotranspiration, soil moisture, percolation and groundwater recharge, ultimately contributing to improved groundwater management. It relies on the integration of a modified Thornthwaite-Mather approach in the root zone and a new form (origin-based) of the Richards equation for modeling of the unsaturated area. Estimation of precipitation and irrigation-originated evapotranspiration enables the determination of the effective precipitation coefficient and irrigation application efficiency, respectively. Meanwhile, precipitation and irrigation-originated components of percolation can be used to estimate coefficients of precipitation percolation and irrigation return flow, respectively. These four coefficients are practically important and necessary for groundwater planning and management. The Zanjan alluvial aquifer, northwestern Iran, is selected as a case study to validate the methodology. Results indicate that the coefficients for precipitation percolation and effective precipitation are estimated to be 27.7% and 73%, respectively, while irrigation application efficiency and return flow are calculated as 87.1% and 12.6%, respectively, during the observation period 2002–2021. Percolation from the root zone occurs throughout the year, except during summer; however, the unsaturated zone reduces the temporal variability of percolated water and leads to a recharge delay of three to six months within the aquifer. Here, groundwater recharge and evapotranspiration are assessed for the entire aquifer due to the lack of spatial distribution of irrigation data and soil properties. However, future works may tend to reproduce spatially distributed data to overcome this main limitation.
Source: Environmental Challenges
Author: Mostafa Naderi
Institution: Institute for Advanced Studies in Basic Sciences
Language: English
Topic: Soil and Unsaturated Flow
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,140
OpenAlex ID: W4415069985